Fix bar chart does not display label at hour 0

What does this MR do?

Fix bar chart does not display label at hour 0 on Commits per day hour (UTC) of Repository Charts

Are there points in the code the reviewer needs to double check?

This fix will convert all label values to string even for non-0 labels which are showed correctly before. This will add slightly extra computation time.

Why was this MR needed?

The label of bar chart at hour 0 does not display on Commits per day hour (UTC) of Repository Charts. This MR will fix it.

Screenshots (if relevant)

Before

After

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #35136 (closed)